Of same place



(No Model.)

W. W. DEAN. TELEPHONE SYSTEM,

No. 590,186. Patented Sept 14,1897.

Wags.

NITED STATES ATENT Fries.

WILLIAM WV. DEAN, OF ST. LOUIS, MISSOURI, ASSIG-NOR TO THE BELL TELEPHONE COMPANY OF MISSOURI, OF SAME PLACE.

TELEPHONE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 590,186, dated September 14, 1897. Application filed July 12, 1897. Serial No. 644,240. (No model.)

accompanying drawing, forming a part ofthis specification.

Myinvention relates particularly to switching mechanism employed at the central ofiice of a telephone-exchange system for including the calling-generator in circuitwith the signal-bells at the subscribers stations and removing the generator from line.

In my applications Serial No. 643,190, filed July 2, 1897, and Serial No. 607,126, filed'September 28, 1896, I have shown and described relay switching apparatus included in a circuit independent of the telephone lines, switching apparatus at the exchange for connecting subscribers for conversation and associating the relay switching apparatus with the called-subscribefs line, in combination with means for operating said relay mechanism to include the generator in circuit with the called-subscribers line, and a second relay controlled by the called subscribers switching apparatus adapted to remove the generator from line.

My invention herein has for its object the accomplishments of the results secured by the aforesaid systems by means of improved interlocking mechanism controlling the association of the generator with the telephoneline.

I will explain my invention by reference to the accompanying drawing, which illustrates the'preferred embodiment thereof.

Upon the left of the drawing I have illustrated a single metallic-circuit telephone-line connected with the substation A, while at the right of the drawing I have shown a party metallic-circuit telephone -line having stations 13 B. At each of the substations is provided a transmitter a, telephone switch-hook '1), receiver 0, and a call-bell 6, preferably of high resistance as, for example, five thousand ohms. The telephone-lines terminate in spring-jacks ff, limbs 1 and 2 of the party line leading to the stations B B being connected, respectively, with line-springs f f The limbs of the telephone-line leading to subscribers station A are similarly connected with the line-springs of spring-jack f. The

signal-bells at stations B B are included in ground branches 3 4, which are respectively connected With limbs 1 and 2 of the line. Two alternate contact-anvils are provided in connection with each of the telephone-hooks which form the terminals of a bridge-conductor across the limbs 1 and 2 of the telephone-line,the bridge-conductor at either station being closed upon the removal of the telephone irom its hook thereat. Condensers g are included in said bridge-conductors. The circuits and apparatus at station A are similar to those at stations B B.

At the central office a pair of switch-plugs is shown, each plug being provided with a tip h and a sleeve 11, adapted to engage the short and long line-springs of the line switches or jacks, respectively. Strands 5 and 6 connect the centralized battery is with the tip and sleeve of the answering-plug Z, while strands 7 and 8 connect the tip and sleeve of connectingplug m with the same battery, whereby the transmitters at the subscribers stations may be supplied with battery-current. Repeating coils k are included in circuit with strands 5 and 6, While repeating-coils 7s are included in circuit with strands 7 and 8. The association of the repeating-coils and centralized battery shown is Well known to those skilled in the art. Strands 7 and 8 also include armatures n and o of magnets and o with their normal contact-anvils, said armatures being in the nature of calling-switches controlled by said magnets. One terminal of each of the magnets is grounded. The remaining terminals of the magnets 71 and o are connected, respectively, with ringing keys or switches q and 0, preferably of the form shown. A grounded battery 5 is adapted to be included in circuit with magnet 01 or magnet 0 upon the depression of keys q or 0', respectively, whereby either armature may be attracted to include the calling-generator in circuit with strand 7 or 8, whereby signaling-current may be directed over limb 2 of the party-telephone line to signal the bell at station B, or over limb l to signal the bell at station 13. The ends of each of the armatnres are preferably insulated and beveled, as shown. A cen trallypivoted catchlever a is disposed between the armatures and normally held against a stop byaretractile spring a. Y Adetent or catch a is provided upon each end of the catch-lever, which engages its armature as it is attracted, and maintains the same in contact with the alternate contact-anvil of the armature which constitutes the terminal of the generator. A magnet t is adapted toactuate the catch-lever to, release the armature and thereby remove the generator from line. An armature to, constituting a switch, is adapted to control the circuit through magnet v,this armature being in a normally open circuit with the batterys and said magnet. A magnet 20, controlling the switch to, is included in the strand 8, a non-inductive resistance 11: being provided about said magnet.

Supposing that subscriber A desires communication with subscriber l3, subscriber A signals the central ofiiee and informs the operator, who depresses her listening-key Z in response to the signal, of the connection he desires. The operator, having previously inserted the answering-plug l into the callingsubscribers spring-jack, inserts the connecting-plug on into the spring-jack of the called subscriber of the party-line and depresses the key 0", whereby circuit is closed through magnet 0, the armature whereof is attracted to include the generator in circuit with conductor 8, limb 1 of the telephone-line, and the signal-bell at the called station. The armature of said magnet upon being thus attracted is engaged by the adjacent catch n whereby the armature is maintained in contact with its alternate contact-anvil. The called subscriber B upon removing his telephone from its switch-hook closes the bridge between the limbs 1 and 2 of the telephone-line, whereby current from generator t finds path from limb 1 at the substation across the bridge to limb 2, thence through conductor 7 and coil k to ground y. The new path for current from the generator is of low resistance, whereby sufficient current is diverted through magnet 20 to cause the attraction of its armature w, whereby circuit from battery 3 is completed through magnet U, said magnet thereupon rotating the catch-lever to disengage the catch from the engaging armature. The armature thereupon is disengaged from its alternate contact-anvil by its retractile spring and the generator removed from line.

If the calling subscriber desires connection with subseriberB of the party-line, the opera tor depresses key q, whereby circuit is closed through magnet 91, the armature whereof is attracted to include the calling-generator in circuit with conductor 7, limb 2 ot' the telephoneline, and the signal-bell at station 13'.

The armature of this magnet is likewise engaged by its catch a after being attracted to maintain the generator in circuit with the signal-bell at station 13. Subscriber B upon removing his telephone from its switch closes the bridgecondnctor between the limbs 1 and 2 of the telephone-line, whereby current from the generator is diverted from limb 2 to limb 1, thence to conductor 8 and coil 7; to ground. The new path for the generator-ctu'rent offers less resistance thereto, additional current being th us diverted through magnet it, whereby its armature is attracted to close circuit through magneto. The magnet 'v disengages the catch from the armature, which then frees itself from the generator-contact.

A clearing-out annunciator .2 is illustrated whose operation will be readily understood by those skilled in the art.

In the claims I use the term signal-bell in the sense of any signal-receivin g apparatus at the subscribers stations.

It is obvious that changes may be readily made from the embodiment of my invention herein shown and described without departing from its spirit, and I do not therefore desire to be limited to the precise apparatus and circuits shown and described; but,

Having thus described my invention, what I claim as new, and desire to seen re by Letters Patent, is

1. In a telephoneexchan ge system,the com bination with a plurality of telephone-lines extending from subscribers stations to an exchange, each subscribers station being pro vided with a signal-bell, of switching apparatus at the exchange for uniting subscribers lines for conversation, a calling-generator, a calling-switch adapted upon being actuated to include the generator in circuit with the bell at the called-subscribefis station, a detent adapted to engage and maintain the calling-switch in the position to which it has been actuated, whereby the generator is maintained in circuit with the called-subscribers bell, means for disengaging said detent and calling-switch, apparatus provided at each station, each apparatus being adapted when its station is the called station to operate said means to disengage the detent and switch, and means for restoring the calling-switch to its normal idle position when thus disengaged, substantially as described.

2. In a telephone-exchange system,the combination with a plurality of telephone-lines extending from subscribers stations to an eX- change, each subscribers station being provided with a signal-bell, of switching apparatus at the exchange for uniting subscribers lines for conversation, a calling-generator, a calling-switch adapted upon being actuated to include the generator in circuit with the bell at the calledsubscribers station, a detent adapted to engage and maintain the callingswitch in the position to which it has been actuated, whereby the generator is maintained in circuit with the called-subscribers bell,an electromagnet for withdrawing the switch being adapted when its station is the called station to operate said magnet, the calling-switch being adapted when thus disengaged from its detent to resume its normal idle position toremove the generator from line, substantially as described.

3. In a telephoneexchange system,tl1e combination with a plurality of telephone-lines extending from subscribers stations to an eX- change, each subscribers station being provided with a signal-bell, of switching appa ratus at the exchange for uniting subscribers lines for conversation, a calling-generator, a calling-switch adapted upon being actuated to include the generator in circuit with the bell at the called-subscribers station, a detent adapted to engage and maintain the callin g-switch in the position to which it has been actuated whereby the generator is maintained in circuit with the called-subseribefis bell, an electromagnet adapted to actuate said switch, means for including said magnet in circuit with a source of current, a second electroinagnet for withdrawing the detent from engagement with the switch, and switches at the subscribers stations, each switch. being adapted when its station is the called station to close circuit through the latter magnet, the callingswitch being adapted when thus disengaged from its detent to resume its normal idle position to remove the generator from line, substantially as described.

4. Inatelephone-exchange syste1n,the combination with a plurality of telephone-lines extending from subscribers stations to an exchange, each subscribers station being provided with a signal-bell, of switching apparatus at the exchange for uniting subscribers lines for conversation, a calling-generator, a

withdrawing the detent from engagement with the switch, and switches at the subscribers stations, each switch being adapted when its station is the called station to close circuit through the latter magnet, the calling-switch being adapted when thus disengaged from its detent to resume its normal idle position to remove the generator from line, substantially as described.

In witness whereof I hereunto subscribe my name this 8th day of July, A. D. 1897.

lV ILLIAM W. DEAN.

Witnesses:

W. E. HARKNESS, FRED R. Mom. 

